When very young children are brought to a doctor or hospital with signs and symptoms consistent with head injury, it is important to determine the cause. For almost 50 years, the triad of subdural haematoma (SDH), retinal haemorrhage (RH) and encephalopathy has been regarded as an accurate predictor of deliberate shaking and widely used to diagnose shaken baby syndrome (SBS). Statistical analyses by Cardiff University researchers and others claim to show that certain combinations of findings are highly predictive of abuse and as a result of this conclusion, protocols such as mandatory reporting to police are invoked in the name of protecting the child. However, concerns have been raised about the circularity of approach used in the statistical analyses which requires each case to be classified explicitly as either abuse or non-abuse. By producing a causal model of the problem, we show that these findings are actually a poor predictor of SBS, even where there is some evidence of risk factors indicative of abuse.

This chapter reviews epidemiological, clinical, and pathological aspects of benign external hydrocephalus, a medical condition that is a risk factor for development of subdural haematoma, and that frequently is mistaken for abusive head trauma (AHT). For infants, there are striking epidemiological similarities regarding gender and age between external hydrocephalus, subdural haematoma (SDH), and AHT/SBS. There is a marked male preponderance, in most infants the symptom debut occurs during the first 6 months, and prematurity appears to be more frequent. External hydrocephalus is known to predispose for development of SDH. Most infants with external hydrocephalus are born with a close-to-normal head circumference (HC) that starts to grow abnormally fast during the first postnatal months; most of these infants reach HC values compatible with hydrocephalus at the age of 2 to 3 months, the peak age at which AHT/SBS most often is diagnosed. Both in infantile SDH and AHT/SBS, the subdural fluid collections appear to be chronic, not acute as one would expect after a traumatic event. There are reasons to assume that external hydrocephalus often has been and will be misdiagnosed as AHT/SBS.

This chapter reviews the evidence showing that short falls may sometimes cause the types of bleeding typically attributed to shaken baby syndrome. Focusing on one seminal article dismissing short falls as a possible cause for fatal injury in infants, it examines in detail the statistical and reasoning errors that allowed the authors to reach their erroneous conclusion, an exercise all the more useful in that these are widespread throughout the literature. Based on numerous publications, the chapter adduces evidence showing that in fact, although they are rare, short falls can be dangerous.

The radiological characteristics of abusive head trauma (AHT) appear to be vaguely defined. A literature search during the period 2008-21 identified 63 articles presenting 172 illustrations with subdural hematomas described as representative of AHT. We evaluated these for signs of benign external hydrocephalus (BEH) or expansive acute subdural haematoma (ASDH). Signs of BEH were widened interhemispheric distance, preserved subarachnoid space and preserved cortical relief despite an overlying SDH, and absence of ventricle compression or midline shift. Signs of an ASDH were hyperattenuating SDH combined with compression of the subarachnoid space, the cortical relief, and ventricles, as well as midline shift. Radiological findings suggesting BEH were detected in 59 illustrations (34.3%). A weaker suspicion of BEH was raised in 32 images. An expansive ASDH was detected in 24 images, and 57 illustrations showed neither signs of BEH nor expansive ASDH or were inconclusive. Males were overrepresented in all groups. Mean age was 4.2 months in the BEH-like group and 17.6 months in the ASDH-like group. BEH complicated by SDH may have been misdiagnosed as SBS/AHT in many of these articles.

Key Learning Points

1. 1. Delineation of the lobes on CT is more difficult than on MRI, and instead they are often referred to as ‘regions’ on CT.

2. 2. Appreciation of the cerebrospinal fluid (CSF) spaces is useful to assess brain volume, mass effect, hydrocephalus and haemorrhage.

3. 3. Subarachnoid haemorrhage (SAH) is commonly seen as abnormal high attenuation within the cerebral sulci, ventricles and/or the basal cisterns.

4. 4. Subdural haematomas (SDH) appear on CT as a concave extra-axial collection (outside the brain parenchyma).

5. 5. Extradural haematomas (EDH) appear as a convex/lens shape and usually underlie a fracture. If the haematoma extends past a suture, it is not extradural.